Characterization of Hydrocarbons in
petroleum fractions using Comprehensive
Gas-Chromatography GCxGC coupled
with Fast Scan Quadrupole MSD
Marc Gibert - Ingenieria Anal´ñitica s.L.
Why GCxGC-MSD in petrochemistry
Which information is in this picture
• Fingerprint of crude oils (based on
bidimensional distribution of more than
1000 compounds)
Light crude oil A
Light crude oil C
Light crude oil GC-MS chromatograms comparison
150000000
100000000
50000000
0
0
5
10
15
20
25
30
0
5
10
15
20
25
30
35
40
45
150000000
100000000
50000000
0
35
40
45
Which information is in this picture
• Fingerprint of crude oils (based on
bidimensional distribution of more than
1000 compounds)
• Chemical information (chemical structure,
volatility, polarity, etc.)
Volatility vs. Polarity
Polarity
Nr name
1 n-hexane
2 benzene
3 cyclohexane
4 n-heptane
5 cyclohexane, methyl
6 toluene
2
1
RT1; RT2 (min)
10.436; 0.715
12.536; 1.277
12.536; 0.766
14.036; 0.817
15.386; 0.868
18.086; 1.635
b.p.°C
69.0
80.1
80.7
98.4
101.0
111.0
6
4
5
3
Volatility
polarity index
0.1
2.7
0.2
0.0
n.d.
2.4
Which information is in this picture
• Fingerprint of crude oils (based on
bidimensional distribution of more than
1000 compounds)
• Chemical information (chemical structure,
volatility, polarity, etc.)
• Information for application purposes
(compound identification for geological
exploration and process refinery uses)
GC x GC method approach
• Goal: use the potentiality of the GCxGC to
obtain as much as possible information and
semplify instrument use for routine analysis
• One GCxGC method is here described:
– to optimise the separation among classes;
– to discrimine among information the more
interesting ones:
–Hydrocarbons group type
–S-containing compounds
–N-containing compounds
Hydrocarbons in light crude oil A
(CH3)2
CH3
Three ring-aromatics
CH3
CH3
(CH3)2
Double ring-aromatics
(CH3)3
Single-ring aromatics
Single-ring aromatics
(CH3)3
(CH3)4
(CH3)5
CH3
(CH3)2
CH3
C30
HC Saturated and Insaturated
C6
C10
C28
C20
C26
GCxGC analysis of light petroleum distillate
Three ring-aromatics
Double ring-aromatics
Single-ring aromatics
HC Saturated and Insaturated
Why to study sulphur compounds
• The increasing concern on the environmental
conditions requires to limit the sulphur level in diesel
fuel and gasoline (e.g. the specification in Europe for
S content is lower than 10 ppm S).
• Very deep conversion of sulphur compounds is
therefore required to produce extremely clean
transportation fuel. Nature and amount of the sulphur
compounds strongly influence the conditions of
desulphurisation treatments.
• The understanding and mapping of these species is
of vital importance for the further treatment of oil and
oil derivatives.
S-containing compounds in light crude oil A
Thioles and sulfides in light crude oil A
1 – dimethyldisulfide
2 – ethyl-methylethyldisulfide
3 – 2-pentanthiol
4 – 1-pentanthiol
5 – 4-methyl, 2-pentanthiol
6 – methyl ethyl disulfide
7 – hexanethiol
8 – tetrahydro thiopyran
9 – hexanethiol
10 – diethyl disulfide
11 – methyl propyl disulfide
12 – cyclohexanethiol
13 – heptanethiol
14 – dimethyl trisulfide
15 – methyl cyclohexanthiol
14
2
1
6
8
11
10
9
4
7
3
5
12
15
13
S-compounds in light crude oil A
Benzothiophenes in light crude oil A
2 – benzothiophene,2,3dihydro
1 – benzothiophene
S
3 – benzothiophene, methyl
S
1
2
S
4 – benzothiophene, 2M
6 – benzothiophene, 4M
S
5 – benzothiophene, 3M
CH
3
S
3
(CH3)2
S
(CH3)3
4
(CH3)4
5
6
(CH3)3
(CH3)4
CH3
(CH3)2
S-compounds in light crude oil A
Dibenzothiophenes in light crude oil A
CH3
(CH3)2
1
(CH3)3
2
3
S
4
1 – dibenzothiophene
S
S
CH3
4 - dibenzothiophene, 3M
2 – dibenzothiophene, methyl
S
(CH3)3
(CH3)2
3 – dibenzothiophene, 2M
64 identified compounds
S-compounds in light crude oil C
Thiophenes in light crude oil C
0 - thiophene
1 – methyl-thiophene
2 – tetrahydro-thiophene
3 – dimethyl-thiophene
4 – methyl-tetrahydrothiophene
5 – dimethyl-thiophane
6 – dimethyl-thiophene
7 – tetra-hydro-thiopirane
8 – dimethyl-tetrahydrothiophene
9 – dimethyl-thiophene
10 – dimethyl-thiophane
11 – cis-2,3-dimethyl-thiophane
12 – trans-2,3-dimethyl-thiophane
13 – dimethyl-thiophene
14 – methyl-tetrahydrothiopirane
15 – dimethyl-tetrahydrothiophene
16 – dimethyl-thiophane
17 – ethyl-tetrahydrothiophene
18 – ethyl-methyl-thiophane
19 – trimethyl-thiophene
3D-VIEW
13
9
3
1
0
6
2
15 16
14
7
5 4 8
10
11 12
17
Benzene
18 19
3D-view: Thiophenes in light crude oil C
S
S
CH3
S
(CH3)2
S
S
(CH3)2
S
CH3
GCxGC S-compound map of
light petroleum distillate (527 ppm S )
36 identified S-compounds
benzothiophene
Benzothiophene,2,3-dihydro
benzenthiol
benzothiophene,methyl
benzothiophene,ethyl
Benzothiophene,2,3-dihydro,3methyl
Thiophene,trimethyl
tetrahydrothiophene
Thiophene,diethyl
thiophene,propyl
thiophene,methyl
thiophene,dimethyl
thiophene thiophene,ethyl
Thiophene, buthyl
Thiophene,diethyl
Thiophene, methyl-ethyl
Tetrahydrotiophene,methyl
Benzothiophene,dimethyl
Benzothiophene,dimethyl
Benzothiophenes 3D-view
Benzothiophene,dimethy
Naphthalene,dimethyl
S
benzothiophene,2,3-dihydro
(CH3)2
Naphthalene,methyl
S
benzothiophene
S
naphthalene
benzothiophene,methyl
S
CH3
S-compound identification: comparison with GC-AED
data
36 S-compounds peaks
GC-MS analysis
16000000000.
12000000000.
Benzothiophene
8000000000.
120000000
4000000000.
.
4600
80000000
4700
16000000000.
12000000000.
8000000000.
40000000
4000000000.
.
4400
4500
4600
4700
0
0
5000
10000
15000
4800
4900
Benzothiophene GC-MS
GC-MS spectrum
Benzothiophene NIST MS
spectrum
134 m/z
134 m/z
Benzothiophene
GCxGC-MS
spectrum
89 m/z
Why to study nitrogen compounds
• During desulphurisation, the presence of refractory
and competitive species as nitrogen compounds is
highly detrimental, due to their effect as inhibitors for
HDS (hydrodesulphurisation) catalysts.
• Neutral (e.g. carbazole), slightly basic (e.g. quinoline)
and basic (e.g. pyridine) nitrogen compounds are
present in gas oil and cracked oil stream. The need
to pre-remove these species is a function of their
nature, the more stringent the removal the more
basic are the species.
• The mapping of the nitrogen species is of vital
importance for the further treatment of oil and oil
derivatives.
N-compounds in Naphtha
N-compounds in Naphtha
N-compounds in Petroleum fraction
H
N
NH2
H
N (CH )
3 3
CH3
pyrrole, trimethyl
(CH3)2
benzenamine, dimethyl
pyrrole, methyl
H
N
CH2CH3
pyrrole, ethyl
NH2
(CH3)
NH2
CH3
H
N
pyrrole
H 3C
H
N (CH )
3 2
N
pyridine, methyl
CH2CH3
benzenamine, methyl ethyl
benzenamine, methyl
pyrrole, dimethyl
(H3C)3
N
pyridine, trimethyl
hexanenitrile
heptanenitrile
pyridine
H3C
N
pyridine, dimethyl
(H3C)2
A7
A6
A8
N
A9
N
H2CH3C
pyridine, methyl ethyl
benzenamine
NH2
A10
A11
A11
N-compounds in Petroleum fraction
N-compounds in Petroleum fraction
H
N
H
N
quinoline, 1,2,3,4-tetrahydro
CH3
1H-indole, methyl
H
N
H
N
CH3
methyl-quinoline, 1,2,3,4-tetrahydro
CH3
Carbazole, methyl
H
N
carbazole
57 identified compounds
GC-MS analysis
60000000
60000000
50000000
50000000
Rt Carbazole 42.123 min
40000000
Carbazole
30000000
20000000
40000000
10000000
0
40
41
42
43
30000000
20000000
10000000
0
0
20
40
60
80
100
120
Carbazole MS Spectra
GC-MS spectrum
Carbazole NIST MS spectrum
167 m/z
139 m/z
Carbazole
GCxGC-MS
spectrum
Development of one GCxGC method
for petrochemical analysis
GCxGC-MSD System
MSD 5973 Fast Scan
Agilent Technologies
ZOEX Dual Stage
Thermal Modulator
GC 6890
Agilent
Technologies
LN2 Zoex
Auto-Fill Unit
GC Agilent Technologies 6890N
• Injector Split/Splittless with EPC
• Split 1:100, carrier Helium
• Primary column: HP-5 MS (25m x 0.25mm ID,
df=0.25μm)
• Secondary column: HP-WAX (0.7m x 0.1mm ID,
df=0.1μm)
• Oven: 40°C x 0.5min, 1.5°C/min to 260°C, 260°C
for 40 min (run time 187 min)
• Ramp Pressure: 20psi, 0.1psi/min to 25psi,
0.55psi/min to 55psi
GCxGC-MSD System
MSD 5973 Fast Scan
Agilent Technologies
ZOEX Dual Stage
Thermal Modulator
GC 6890
Agilent
Technologies
LN2 Zoex
Auto-Fill Unit
ZOEX dual stage thermal modulator
•
•
•
•
KT-2004 Zoex Dual Stage Thermal Modulator
LN2 Zoex Auto Fill Unit
Zoex GC-Image Software
Modulator Tube: uncoated fused silica tube 2mt X
0.1mmID
• Modulation period: 9 seconds
• Modulation duration: 450 msec
• Hot Jet Temperature: 350°C
ZOEX modulator
operation
GCxGC-MSD System
MSD 5973 Fast
Scan Agilent
Technologies
ZOEX Dual Stage
Thermal Modulator
GC 6890
Agilent
Technologies
LN2 Zoex
Auto-Fill Unit
MSD 5973 Fast Scan Agilent
Technologies
• In order to maximize the spectral information,
full-scan mass spectra acquisition mode (EI)
was used
• MSD 5973 inert with Performance Electronics
for Fast Scan Capabilities (10,000 amu/sec)
and improved sensitivity
• Range 45-350 amu (19.80 scan/sec)
• MS Transfer line: uncoated fused silica tube
(0.8m x 0.25mm ID, temperature 280°C)
Development of one GCxGC method for
petrochemical analysis
How many variables in setting up a GCxGC method?
Columns choice (stationary phase and lenght)
Main oven temperature and/or secondary oven temperature
Column flow
Modulation period and duration
Cold and Hot jet flows
Simplify the user operation maintaining fixed the conditions
for all type of compounds in oil-derivatives
Column choice
• Column combination to maximize GCxGC
potentiality: the most “bi-dimensional” stationary
phases must be used
Primary column: apolar
Secondary column: polar
• Separate wide variety of hydrocarbon compounds
(saturate/insaturate, light up to heavy aromatics and
heteroatom compounds)
• Which stationary phase and column lenght?
• Wax : polyethylene glycol
• DB-1701: 14% cyanopropyl-phenyl, 86% dimethylpolysiloxane
• HP-17: 50% phenyl, 50% dimethylpolysiloxane
Secondary column 1 mt x 0.1 mmID x 0.1 um DB-1701
Oven: 35°Cx0min, incr. 2°C/min to 300°C for 10 min
No secondary oven
Modulation period : 6 sec.
Three ring aromatics
Naphtalene
byphenyl
1 meter DB-1701
Secondary column 1 mt x 0.1 mmID x 0.1 um HP-17
Oven: 40°Cx0.5min, incr. 2°C/min to 300°C for 10 min
No secondary oven
Modulation period : 9 sec.
byphenyl
Naphtalene
1 meter HP-17
byphenyl
Three ring aromatics
Naphtalene
Three ring aromatics
Secondary column 2 mt x 0.1 mmID x 0.1 um WAX
Oven: 40°Cx0.5min, incr. 0.5°C/min to 260°C for 40 min
Secondary Oven: 30°C above main oven
byphenyl
Modulation period : 9 sec.
2 meters WAX
Naphtalene
Wrap-around
Three ring aromatics
Secondary column 1 mt x 0.1 mmID x 0.1 um WAX
Oven: 40°Cx0.5min, incr. 0.5°C/min to 260°C for 40 min
Secondary Oven: 30°C above main oven
Modulation period : 9 sec.
0.7 meter WAX
Three ring aromatics
byphenyl
Naphtalene
Modulation period
•
Large enough to permit the elution of all the components from the
secondary column (y- axis, separation by polarity)
•
Should be tuned to collect at least three fraction of the eluting
primary column peaks (high modulation period values require wide
primary column peaks)
Modulation period
Three ring aromatics
byphenyl
9 seconds mod. period
Naphtalene
Modulation period
Nr name
RT1; RT2 (min)
1 benzene
2 ciclohexane
12.536; 1.277
12.536; 0.766
1
2
b.p.°C
80.1
80.7
Modulation period
2 nd modulation
1
Ciclohexane
Benzene
3 rd modulation
1 st modulation
4 th modulation
Conclusions
• The GCxGC-qMSD showed to be a powerful tool in
light petroleum fraction investigation. Its use allows
the separation and identification of different polarity
hydrocarbons (aromatic vs aliphatic) together with
unique identification of heteroatom compounds, with
a single sample run and without changing any
analytical set up and parameters.
Thank you for your attention